Simple and Sustainable Seafood Swaps

The Gills Gals, Becky and Gemma, always try and find the tastiest seafood that support sustainability. Read their easy sustainable swaps to help your seafood choices. 

Amongst UK adults who eat seafood, 47% claim to regularly (at least once a month) eat cod, 39% regularly eat salmon, 37% tuna, 26% haddock and 23% prawns. They have been labelled the Big Five and make up between 60 and 75% of all seafood eaten in the UK (numbers change depending on time of year and source). This huge percentage is mainly due to availability, but also demand from the British public and retailers wanting to stock what sells. However, there’s such a huge amount of seafood waiting to be discovered and they can often be more sustainable and cheaper as well as offering up a a new flavour.

We use the Good Fish Guide app to help us when doing our shopping. You simply type in the fish you were looking to purchase and it will be labelled either green (sustainable), yellow (things to look out for) or red (best to avoid). It’s also worth talking to your fishmonger about what’s in season and seeing if they have any cooking inspiration for you – ours always comes up with something new we haven’t cooked with before!
fish tacos


Cod became a bit of a dirty word in the seafood industry after years of over-fishing left this fish far from sustainable. However, back in July 2017 North Sea cod was awarded sustainable status by the Marine Stewardship Council for the first time in 20 years. Whilst we can tuck into some cod with a clear conscience, overeating of one species can lead to problems down the line. Due to the popularity of cod, according to Seafish it is one of the five most commonly eaten fish in the UK, prices tend to be higher for this white fish.  

The swap: Coley

Coley is a brilliant substitute for cod. It is classified within the same family as cod and can be used in much the same way. Coley is a sweet, firm white fish with a grey tinge. It tends to be a little meatier than cod, which lends itself well to fish pies, tacos and stews. As with all fish look for the MSC certification to ensure it was caught sustainably.

Cooking inspiration: Fish Tacos


Salmon is SO overused. Weddings, brunches, canapes. Salmon and smoked salmon tend to be the old reliable choices. We’re used to it, even people who ‘don’t like fish’, like salmon. Whilst it is a great source of omega 3, being an oily fish, the overwhelming demand for this fish can lead to it being farmed and caught unsustainably and, similarly to cod, this demand drives up the cost. We’re not saying all salmon is bad, checking for MSC certification is crucial in selecting this fish, but why not try something different? It’s bound to jazz up that predictable scrambled egg pairing.

The swap: Rainbow

Sea trout would be the closest match to salmon, but at the time of writing it’s not a green certified fish so we have selected rainbow trout. Rainbow trout is the most popular farmed species of trout, with most of production occurring in a variety of enclosures in freshwater. Flavour wise, it is very similar to salmon but the texture of this fish is a little more delicate.  Buying organic farmed trout is the best choice to make with regards to sustainability as fish stocking densities are generally lower in comparison to non-organic farms, feed is sourced sustainably and welfare of a high standard.

Cooking inspiration: Pancetta Wrapped Trout


Haddock is best known for being served up in chippies up and down the country, often alongside cod. However, mid last year the MSC took some haddock fisheries off the sustainable list, causinghake controversy in the fishing industry. Whilst you can use the good fish guide to check on the sustainability of haddock before you purchase, there are also plenty of options if you want to try something a little different.

The swap: Hake

Hake is a member of the cod family, but has a slightly more subtle taste. It is a firm, white fish and can be perfectly substituted in cod recipes. It has a medium flake, so won’t fall apart and will hold its shape in your dish. Due to its subtle flavour, it can stand up to bold ingredients, and is a popular fish in Spain matched alongside the likes of chorizo and paprika. As we would recommend with all of your seafood purchasing you need to be looking out for that MSC logo and it’s best not to purchase during its breeding season which runs from February to July.

Cooking inspiration: Pan-fried hake with a red pepper relish


Tuna is a staple of a Brit’s diet – whether it be in a sandwich, on a jacket potato or as a steak served with a stir fry. However, tuna is at risk and needs to be cut down on significantly in order to replenish stocks (with the exception of line-caught skipjack tuna). Another concern to be aware of when eating tuna is whether it is dolphin friendly. Whilst you should absolutely ensure that it is, people often assume that this means the tuna is ok to eat. Whilst it does mean the fishing methods are better in that respect, it doesn’t cover if it is from a sustainable environment so be sure to check that too.

The swap: Mackerel

Tuna is pretty unique, especially in steak form. However, mackerel packs just as much, if not more flavour, and is actually part of the same group of fish as tuna. Best eaten as fresh as possible it’s packed full of omega-3 fatty acids. It works well in asian style dishes, and matches perfectly with tart flavours such as rhubarb or apple which cut through the oiliness of the fish. Used raw (as fresh as possible) it also works well in sushi.

Cooking inspiration: Mackerel with rhubarb sauce


There are so many prawns to choose from, each with their own fishing method and things to look out for. However there’s just nothing that compares! Rather than swapping prawns for another seafood below are the markers to look out for when shopping for your shrimp.

What to look out for:

Things you should consider when shopping for prawns is if they are from a low stocking density, and therefore not being over farmed. Even better is if the prawns are able to swim in a natural environment, with plenty of space – as you would want from something like beef or chicken.

It can be confusing so the most important thing to look for is that MSC or ASC tick!

Cooking inspiration: Prawn Coconut Curry

Written by Becky and Gemma from Gills Gills Gills – a blog encouraging people to cook and eat sustainable seafood.


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